Question: A box contains $9$ red marbles, $7$ green marbles, and $8$ blue marbles. If a marble is randomly chosen, what is the probability that it is not red?
Explanation: There are $9 + 7 + 8 = 24$ marbles in the box. There are $9$ red marbles. That means $24 - 9 = 15$ are not red. The probability is $ \frac{15}{24} = \dfrac{5}{8}$.